Thermostatic controller



Nov. 18, 1 24- 1,515,684

A. J. KERCHER THERMOSTATIC CONTROLLER 7 Filed March 26. 1923 2 v FIE! E Sheets-Sheet l I5 /4 26 22 2e I? 38 42 4 4/ $4 47 f as 44 42 1.9 4 77;- 33 72 64503655 2 A. J. KERCHEF? THERMOSTATIC CONTROLLER Filed March 26. 1923 2 Sheats-$hcet 2 Patented Nov. 1924.

- UNITED STATES "1,515,684 PATENT OFFICE.

ARTHUR J. KERC HER, OI" BERKELEY, CALIFORNIA.

rnmmosm'rrc commune.

Application filed March 26, 192th "Sertal Ko. 827,861.

' troller, of which the following is a specificato vary its point to the temperature.

that may'readil and notion. Still another ob tion.

I This invention relates to a temperature responsive controller, and more particularly possible to adjust so as of response with respect Such a device is especially useful in connection with heating appliances, for controlling the heating elements, and I shall describe it as used on an electrical cooker, where it serves to maintain the cooking temperature at any value that is variable within limits.

It is one of the objects of m invention to provide a thermal contro ler that is simple and inexpens've. Another object is to provide a controller of this type quickly be adjusted ject is to'improve in tion and operation of nism.

Still another object is to make it 1n ath general the constructhis type of mechapossible, ermostat utilizing a readily volatilizable liquid in a closed cell, to vary the temthe controlling function is effected. v

My invention geous features, some of which with the foregoing, will. be set forth at length in the following description, where I shall outline in e invention which I have selected for illustration in the drawmgs accompanging and formingpart of my presentv s ci cation, Although I have shown in t e drawings but one embodiment of my invention, it is to be. understood I do not desire to be limited the invention as expressedin be embodied in other forms also. 1-

Referring to the drawings: 7

igure 1 is a side elevation of a cooker equipped with a thermal controller constructed in accordance with my invention, my device;

and illustrates'one adaptation 0 Figure 2 1s a top plan-view of'the cooker shown in Fig. 1;- 3

Figure 3 isan enlarged sectional view 2 taken along the plane 33 of Fi 1, showingthe thermostat in closed position;

possesses other advanta-P the claims may f Figure 4 is an enlarged fragmentary view taken from the bottom of the cooker;

igure 5 is an enlarged fragmentary sectional view similar to Fig. 3, but showing the thermostat switch in open position;

igure 6 is an enlarged sectional view showing how the thermostat may be adjusted for var ing the cooking temperature; and Figure is a diagram of connections for the cooker.

' The cooker 11 is in the form of a cyindrical body, and includes a cooking chamber 12 formed within a conta'mer or vessel 13. is vessel is preferably made from sheet metal such as copper or aluminum, and is of any convenientsize. The food to be cooked is first disposed in a that is adapted to be accommodated within the chamber 12.

passing wall 15 is disposed about this vessel.

heating elements 14. This wall 15 is appropriately fastened near its top to the open end of instance the space 17 formed between the walls is shown as not completely filled with heat insulating material, such an arran ment may be used if desired, in lieu of. the sheets 0 insulating material 18 shown in Fig. 3.- The wall 15 is extended to form a base 19 within which the control elements he device may be aecomodated. The top of base 19 also forms an annular rim 20 around the bottom of wall 15, which rim serves as a rest or support for the cover 21. This cover. is double walled as indicated, and telescopes over the chamber '12. Be tween the double walls, insulating 22 is packed. Furthermore the telescoping is purposely made loose,

3' being provided on the exterior of wall 15 to space the cover therefrom. The Surfaces of contact on rim 20 and the bottom of cover the presentinstance in vessel 13, an encomknobs or projections the vessel 13, as by the seaming 16. Although in the presentas by the aid of 22 are' purposely sloped towards the center,

Th structure of the cooker as thus outlined is described in greater. detail and claimed in a divisional application entitled Electric cooker, filed in 111 'name on 'Sept. 29, 1923, and having Serial 0. 665,703.

The supply of electric current to the heating elements is efi'ectedby' the aid of a connection block 27 held on the base 19. In the present instance this block is shown as made up of two parts which are disposed one on the inside and the other on the outside of the base, and clamped together, as by the aid of screws 28 passing through the base. This conneotion'block has a pair of contact posts 29 which are below the surface of the block and located in bores 30-therein. Into these bores, appropriately formed plugs may be inserted to contact with the posts 29.

As shown most clearly in the diagram 0 connections, the circuit for the heating elements 14 which connects to the posts 29, is controlled by a switch 31 having relatively movable contacts 32 and 33. The stationary contact 32 is insulated from and supported by a metallic plate 34,- and connects, a lead 35, to the lower post 29. The movable contact ma be supported on a lever 36; a short lead 37, insulated by beads 72, connects this contact with another stationary insulated contact post 38; to which one lead 39 of the heating elements 14 is connected. The other lead 40 from these elements upper post 29. in Fig. 1, and posts 29 connected to an external source, the elements 14 are active, their circuit being completed as follows from lower post 29, lead 35, stationary contact 32, movable contact 33, lead 37, post 38,

lead '39, heating elements 14, to upper post 29. In order to indicate whether the heating elements are active or not, I provide a small pilot light 41 disposed in a socket 42 in the block 27 which is connected in parallel .to the lead 35. This lead is purposely resistance so as to provide a large enough dropin potential fli llgllt the lamp when current is being suppie The switch 31, with its associated parts, is located below the chamber 13 and is concealed by a tubular extension 42- projecting from the bottom of the wall 15, and a cover 43 for this extension. This cover 43 is held in lace by aid of a plurality of screws or stu s 44, which pass through the bottom of chamber 12 and posed therein. These studs may also coni the connects directly with the With the switch closed as p a reinforcing plate 45diaveniently serve to support the late 34 rigidly, as for example by the. aid of bushings 46 disposed thereon and nuts 47 engaging the studs. Furthermore the extension 42 is apertured at one side, as indicated at 48, Fig. 5, for accommodating the insulation bushings 49, 50 and 51 which are used .to lead the connections from theblock 27 to the space defined by the extension 42 and its cover 43. e

. In order to guard against undesirable or dangerous temperatures in the cooking chamber 12, a thermostat controller embodying my invention, is arranged to open the switch upon the attainment of a definite temperature therein. When the switch opens, the heating elements 14 are deenergized, and remain so until thetemperature recedes to a lower value. Upon this occurring, the switch is permitted to close again. The cycle of operations may then be repeat ed many times until some other agenc causes the circuit to be finally interrupted somewhere externally of the cooker, itself, as for example by withdrawal of the plugs from posts 29. The. thermostat is arranged so that it is acted upon by the temperature developed in chamber 12, andnot to any material extent b the temperature developed' immediatel" adjacent the heating elements. It is evident that \in this way the actual-cooking temperature may be controlled to a nicety. To accom lish thiszresalt, the thermostat is arran ed in close .heat conducting relation with the bottom of chamber 12. I prefer to employ a thermostat utilizing a readily volatilizable fluid in an enclosed chamber, such as defined by the cell 52. Thiscell is placed adjacent the bottom of the chamber 12, so that it may be in as good thermal conductive relation with the cooking food as practicable. The cell 52 has resilient metal disc faces such as sprin copper, which may be expanded or force out by the pressure exerted in the cell due to the volatilization of the liquid therein. The cell 52 is held in lace against the bottom'of the chamber 12 y soldering. Expansion of the cell to a sufiicient. degree causes the contact'33 to move away from the. stationary contact 32- and to open the heating element circuit. Fig. 3 shows the cell 52 in a condition when it has not expanded sufliciently to operate the movable contact 33, while Fig. 5 shows the 'cell expanded sufficiently to move the contact 33.

' The mechanical connections whereby the expansions and contractions of the cell 52 the-lever 36. Furthermore this lever is biased yieldingly to closed position, and for point-of application of the force. Fig. 6

' th s purpose a counterweight 56 is fastened illustrates this position, which corresponds to an arm 57 of the lever 36. I prefer to to a low temperature adjustment, since loss provide, as one of the elements in the me-' force need be exerted by the cell to exert chanical connection from the pressure cell a large enough torque on the spring for 52 to the switch arm 36, a buckled leaf urging it to the position of Fig. 5. The left spring 59; this spring 59 is arranged so that hand foot 64 is provided merely for supit .may press against a projection or pin porting the-slide 63;the force exerted there- 60 fastened to the lever 36 and extending by on the spring is of no substantial value into a space 58 formed in the support 54' since it is always at a considerable distance adjacent the plate 34; This space-may also fromthe pin 62. Furthermore due tothe be conveniently used for accommodating the large flexure of spring 59, the force exerted. spring 59, the ends of which are shown as by the right hand foot has influence in ti'rnanchored in the end walls of the space. The ing the spring only about its right hand buckling of the spring is so adjusted that anchored end, and no appreciable influence its stable position corresponds to that shown as regards the left hand end; In an analoin'Fig. 3, or, Fig.6, where it is arched awaygous manner, the left hand foot, which is as from the pin 60, and thus permits the switch before stated used, merely for supporting the contacts to remain closed. The buckling of slide 63, -has no appreciable effect in assistthe spring so'that its arch coacts with the ing the torque exerted by the right hand tionary contact 32 is unstable, and it can be spring: 59.

' aperture in the sup ort 54.

pin 60tourge contact 33-away from the stafoot about the right hand end of the held in this position only by the force exert-' By referring to Fig. 4, one manner in ed on the spring 59 by the expanding cell which the slide 63 may be adjusted, is in- 52. In order to adjust the buckling of the dicated. The slide has an extension- 65 in spring, a set screw 61 is provided for exertwhich there is an aperture 66. Into this mg a force against one end of the spring aperture the end of the arm 67 of a pivoted 59, as by threading into an appropriate lever 68 is turned. This lever is pivoted on a pin 69 held onthe stationary plate 34.

e expansion 0 cell 52, if sufi'iciently It is evident that by rotating thisle'ver, the great, effects the buckling of spring'59 so slide 63 may be adjusted. The arm 70 that it may be sprung'to the position of serves as a convenient means for effecting "increased, since it is measured from the 3. In a thermostat,.a buckled spring hav- Flg. 5, and since this buckling is in the na-' this result, and for; ease in manipulation,- ture of a snap action, the contacts open this arm-extendsthrough appropriate slots quickly. (Conversely, upon a slight contracin the extension 42 and base 19 so that it is tion of the cell 52, the spring returns to its accessible from the outside of the cooker. stable position of Fig. 3, and permits the I prefer to provide an arcuate guide 71 cut contacts to close. v in the plate :34 for accommodating the end Although any of several different kinds of arm 67 50 that this end may project a of mechanical .connection'simay be employed. considerable distancethrough the extension 106 between the cell 52 and the sprin 59 to 65 of slide 63.

effect this result, I prefer to make t is con, claim:

nection adjustable, so asto'vary the lever- 1-.' n a therm stat, a member. movable age of the force exerted by the expanding .in response to temperature variations. a

cell. In this way the temperature at which buckled spring, a mechani 1 on n 9' the thermostat operates may be controlled. tween'thc'member and spring, whereby upon or this purpose, there is interposed between sufficient movement of the member, the. a projection or pin 62 of the cell 52, and the spring may be sprung over, and means for spring 59, an adjustable slide 63. This setting the mechanical connection so as to slide-has a pair of feet 64 resting on the determine the point ofapplication of the spring, and a back cooperating with pin 62 force exerted by the member on the spring, of cell 52. The; feet 64 are separated by an whereby the temperature at which the spring appreciable distance, so that they each are operates may be controlled. adjacent respectively to the anchored ends 2. In a thermostat, a member movable of spring 59. One ofthe'feet, such as 64 is 1n response to temperature variations, a much closer to the pin 62, and serves to buckled "spring arranged to be sprung over transmit substantially all of the force to the on a predetermined movement of the memspring which is exerted by the cell 52. By her, and means for varying the temperature movin the slide 63 so as to bring this right at which thespring is operated, comprising hand oot 64 nearer the in 62, the iorce. a variable mechanical connection between exerted by this foot on t e spring 59 a the'member and'the spring for varying the preaches that exerted by cell 52, and at tiie leverage of the force exerted by the member same time, the lever arm of this force is also on the spring.

right hand anchored end of spring 59 to the ingia stable arched position and all-opposite unstable arched position, a member movable,

in response to temperature variations for controlling the buckling of the spring, and means for varying the efiect of the member on the spring.

- 4. In a thermostat, a buckled spring having a stable arched position and an opposite unstable arched position, a circuit controller operated'by the movement of the spring, a member movable in response to temperature variations for controlling the buckling of the spring, and means for varying the effect of the member on the spring.

5. In a thermostat, a pressure cell expan sible in response to temperature variations, a buckled spring adapted to be sprung over on a predetermined expansion of said cell, and means whereby the force of expansion of the cell necessary to operate the spring may be varied, comprising a member adapted to contact with the spring at an adjustable point of contact.

6. In a thermostat, a buckled spring having a stable arched position and an unstable arched position, a pressure cell expansible in response to temperature variations for controlling the buckling of the spring, and means whereby the force of expansion of the cell necessary to operate the' spring may be varied.

7 In a thermostat, a buckled spring having a stable arched position and an opposite unstable arched .position, a circuit controller operated by the movement of the spring, a pressure cell expansible in response to temperature variations for controlling the buckling of the spring, and means whereby the force of expansion of the cell necessary ,to operate the spring may be varied.

8. In a thermostat, a buckled spring adapted to be sprung over, a member for transmitting a force to the spring adjustable so that the point of application of the force to the spring may be varied, and a temperature responsive element operating the membermechanically and supplying the force for buckling the spring.

9. In a thermostat, a buckled spring having a stable'arched position and an opposite unstable arched position, a member for transmitting a force to the spring adjustable so that the point of application of the force may be varied, and a temperature responsive element operating the member mechanically and supplying the force for buckling the spring.

' 10. In athermostat, a buckled spring having a stable arched position and an opposite unstable arched position, operated by the buckling of the spring, a member for transmitting a force to the spring adjustable so that the point 'of application of the force may be varied, and a temperature responsive element operating the a circuit controller member mechanically and supplying the force for buckling the spring.

11. In a thermostat, a buckled spring adapted to be sprung over and thereby pcrform a controlling function, and means for operating the spring in response to temperature conditions comprising a .slide adjustably mounted on the spring, whereby it has an adjustable place of contact therewith, and a temperature responsive element adapted to exert a force against said slide.

12. In a thermostat, a buckled spring having a stable arched position and an opposite unstable arched position, an electric switch operated by the movement of the spring from one position to another, a support in which the ends of the spring are anchored, a slide having two feet contacting with the spring respectively near the points where they are anchored, a lever having an arm for adjusting the slide on the spring, and an expansible pressure cell arranged to transmit a force due to its expansion to the slide at a point relatively nearer to one of the feet than the other.

13. In a thermostat, a member movable in response to temperature variations, a device arranged to be operated by the force exerted by the movable member, and means for varying the temperature at which said device is operated, comprising a lever arm, and means operated bysaid arm the force exerted by the movable member on the device.

1 1-. In a thermostat, a closed pressure cell expansible in response to temperature rise, a device arranged to be mechanically operto vary the leverage of ated by the force of expansion of the cell,

the cell on the device.

15. In a thermostat, a member movable in response to temperature variations, a buckled spring arranged to be sprung over by the force exerted by the movable member, and means for varying the temperature at which said spring is sprung over, comprising a lever arm, and means operated by said. arm to vary the leverage of the .force exerted by the movable member on the spring.

16. In a thermostat, a closed expansible in response to temperature rise, a buckled spring arranged to be sprun over by thefor of expansion of the cel and means for varying the temperature at which said spring is sprung over, comprising a lever arm, and means operatedby said arm to vary. the leverage of the force exerted by the cell on the spring.

In testimony whereofi I have hereunto set in hand. y ARTHUR J. KERGHER.

pressure cell- 

